Hull form



pr 1944- w. s. BURGESS 2,347,077

' HULL FORM Filed May. 21, 1941 -2 Sheets-Sheet 1 Patented Apr. 18, 1944 UNITED STATES PATENT o FICE signor to Weaver Associates Corporation, Washington, D. 0., a corporation of Maryland Application May 21, 1941, Serial No. 394,549

15- Claims. (01. 114-.-'5e) This invention relates to hull forms and in particular to displacement type hull forms for cargo ships, passenger ships, naval vessels and yachts. The main object of the invention is to provide a hull form characterized by simplicity and by su-' perior speed horsepower efficiency. In order that the invention may be clearly understood, I shall described it with reference to an embodiment shown by way of example in the accompanying drawings. In these drawings: 1

Figure 1 is an elevation of a hull embodying the features of the invention; 7

Figure 2 is a body plan of the hull of Figure 1;

Figure 3 is a body plan on an enlarged scale of the starboard half of the iorebody appearing in Figures 1 and 2. V

Figure 4 is an elevation of the forebody portion of Figure 3, and

Figure 5 is a diagramshowing the forebody sections at the stations as numbered in Figure 3, these sections, however, being those of the port forebody half. I

Referring to the drawings and first to Figures 1 and 2, the illustrated hull comprises a forebody ill, a middlebody ll, and an afterbody l2. The sides of the body portions are vertical and straight on topand the 'bottomis flat, the sides and bottom being joined by bilges of novel form which will be described in detail hereinafter. As here shown, the forebody is provided with bow sponsons. {3 and. I4, but this provision is a matter of choice. Essentially the forebody and afterbody, as here shown, are duplicates, the sides of each being mutually approached throughout to a point, so thata double-ended boat of relatively sharp contours, as seen in plan view, is provided. The sides of the middle body are parallel.

The middle body bilges, as at Ila, are relatively hard and the side and bottom tangency lines of each bilge are parallel. The forebody bilges start with theradius 1', Figures 3 and 4, of the middle body bilges, but this radius progressively increases forwardly throughout to R, Figure 4, withthe result that the side tangency line l5 inclines upwardly and forwardly .throughout while the bottom tangency line [6 inclines inwardly toward the longitudinal center line and forwardly throughout. The starboard tangency lines I5 and I6 are indicated in Figures 3 and 4, while the port tangency lines I! and [8 of the forebody appear in Figure 5, the lines l5 and I6 defining the starboard bilge l9 and the lines l1 and I8 defining the port bilge 20. These bilges may be conceived of as quarter sections of a truncated cone bent longitudinally along the forebody curves with the longitudinal central element of the conical surfaces intersected by lines bisecting the right angles between the sides and the bottom.

The afterbody bilges, as at In, are identical with the forebody bilges, their tangency lines being continuations' of the tangency lines of the parallel mid'dle:body,lthe tangency lines of each afterbody bilge diverging rearwardly in the identical manner in whichth'e tangency lines of the forebody bilge's diverge forwardly. In other words, the forebody bilges are on a radius which increases progressively forwardly while the after body bilges are on identical radii which enlarge rearwardly.

With the bilges formed as described, the bottom tangency lines of the forebody bilges-terminate at about station 4, Figure 4, at the central vertical longitudinal-plane in an upwardly and forwardly elliptically curving central bow-line 2| which terminates in the vertical stem line 22. The afterbody has'a line 23 identical with line 21' terminating aft in'a vertical stern line 24.

While the foreand afterbody contours may vary to some extent in degree of sharpness, I have determined that the best proportions are arrived at by the formula y being the half breadth. in feet of the foreor afterbody at a given distance a, in feet,'forward or aft of the middle body, as the casemay be. 1 being the given length of the foreor afterbody; and B being the given middle body beam, or what is the same thing, the beam of the foreor afterbody immediately at the middle body. Y

.For the bestresultsthe following proportions are typical: overall length (excluding overhang), L, 240 feet; length, l; of foreorafterbody, each 84 feet; length of middle body, 72 feet; beam, B,

38 feet; depth 20 feet; LWL midway between top and bottom; radius r of middle body bilges and minor radius of fore-and afterbody bilges 2 feet; major radius R of fore and afterbody bilges, at their extremities, 6 feet. Theseproportions may be maintained in hulls of all sizes. In general B=15.83% .L;- 1:35% of L; length of middle body- L 2l; v

inajor bilge radius R=i' The foreand afterbodyplan is determined by the formula y abovegiven. With E equal to38 feet and 1 equal to 84 feet the value for y at a distance at of, for example, 5 feet forward or aft of the middle body would solve out from the followi-ng;

foreand afterbody bilges merge but become rel atively easy toward the bow and stem. The sides are vertical throughout, excluding excrescenses such as the sponsons l3 and i4, and are parallel.

at the middle body and the bottom is flat. Consequently all underbody sections comprise straight side and bottom elements tangential to the are at the bilge. I do not wish to be limited to strict adherence to the specific proportioning and forms hereinbefore mentioned since, as will be understood, there may be some' deviation in these respects without fatal impairment of the advantages arising from full adherence to the proportions given in the example. It is furthermore to be understood that I have given the figures for a 240 foot boat merely by way of example. The invention may be embodied in ships or boats of any size, and utilized for any purpose. With these points in mind the scope of the invention is determined in the following claims.

I claim:

1. A displacement type hull including foreand afterbodies and a middle body, said middle body having rounded bilges throughout, the forebody having forwardly converging rounded bilges starting at the middle body on the same radius as the forward end of the middle body bilges and running forward with increasing radius and length of arc, and the afterbody having rearwardly converging rounded bilges starting at the middle body on the same radius as the after end of the middle body bilges and running aft with increasing radius and length of arc, all bilges being convex throughout. I

2. A displacement type hull including foreand afterbodies and a middle body, said middle body having rounded bilges throughout, the forebody having forwardly converging rounded bilges starting at the middle body on the same radius as the forward end of the middle body bilges and running forward with increasing radius and length of arc, and the afterbody having rearwardly converging rounded bilges starting at the middle body on the same radius as the after end of the middle body bilges and running aft with increasing radius and length of are, all body portions having straight side and bottom portions tangential to their bilges and all bilges being convex throughout.

3. A bull according to claim 1 wherein the forebody sides approach each other forwardly substantially in accordance with the formula where y is a half-breadth in feet of the forebody at at, a: being a given distance in feet forward of the after end of the forebody, I is the given length of the forebody, and B is the beam.

4. A displacement type hull including foreand afterbodies and a middle body, said middle body having rounded bilges throughout, the forebody having forwardly converging rounded bilges starting at the middle body on the same radius as the forward end of the middle body bilges and running forward with increasing radius and a constant arc of 90, and the afterbody having rearwardly converging rounded bilges starting dle body having bilges rounded on a uniform radius throughout, the forebody having forwardly converging rounded bilges starting at the middle body on the same radius as the middle body bilges and running forward with increasing radius and length of arc, and the afterbody having rearwardly converging rounded bilges starting at the middle body on the same radius as the middle body bilges and running aft with increasing radius and length of arc, all bilges'being convex throughout.

6. A displacement type hull including foreand after-bodies and a parallel middle body, said mid-- dle body having bilges rounded on an arc of throughout, the forebody having forwardly converging rounded bilges starting at the middle body on the same radius as the middle body bilges and running forward with increasing radius and a constant arc of 90, and the afterbody having rearwardly converging rounded bilges starting at the middle body on the same radius as the middle body bilges and running aft with increasing radius on a constant arc of 90, all bilges being convex throughout.

'7. A displacement type hull including foreand afterbodies and a middle body, said body Fortions all having rounded bilges and straight side and bottom portions tangential to the bilges; the said side portions of the forebody approaching each other forwardly to a point and those of the afterbody approaching each other rearwardly to a point, the bottom tangency lines of the middle body being parallel, those of the forebody approaching each other forwardly, and those of the afterbody approaching ach other rearwardly; the side tangency lines of the middle body being horizontal, those of the forebody rising forwardly, and those of the afterbody rising aft, all bilges being convex throughout.

8. A hull according to claim 7 wherein the bilges are arcuate and the arc of the forebody and middle body bilges is 90.

9. A hull according to claim 7 wherein the approach toward each other of the bottom tangency lines of the forebody is more rapid than the approach toward each other of said forebody side portions, and the approach toward each other of the bottom tangency lines of the afterbody is more rapid than the approach toward each other of said afterbody side portions.

10. A displacement type hull including foreand afterbodies and a middle body, said middle body having rounded bilges throughout; the forebody being pointed and having rounded bilges throughout merging at their after end with the middle body bilges, said forebody having sides and a bottom including straight portions tanential to its bilges, the side tangency line of each forebody bilge inclining upwardly and forwardly throughout and the bottom tangency line of each forebody bilge inclining inwardly toward the longitudinal center and forwardly throughout, said bottom tangency lines terminating forwardly in an upwardly curving line in the longitudinal center plane; the afterbody tapering aft and having rounded bilges merging at their forward ends with the middle body bilges, and having sides and a bottom including straight portions tangential to its bilges, the

side tangency lines of the afterbody bilges rising aft and the bottom tangency lines of the afterbody bilges approaching each other aft; and all bilges being convex throughout.

11. A hull according to claim 10 wherein the middle body bilges are rounded throughout on a constant arc of 90 and the forebody bilges are rounded on an arc of 90 with a radius progressively increasing forwardly.

12. A displacement type hull including foreand afterbodies and a middle body, all underbody sections comprising straight side and bottom elements tangential to an are at the bilge; the said are being uniform for all middle body sections, increasing in radius and length forwardly in the forebody, and increasing in radius and length rearwardly in the afterbody; and all bilges being convex throughout.

13. A displacement type hull having vertical sides throughout and a flat bottom, said hull ineluding a forebody whose sides approach each other forwardly throughout to a pointed bow, said forebody having quarter-round bilges whose radius progressively increases forwardly throughout, an afterbody whose sides approach each other rearwardly throughout to a pointed stern, said afterbody having quarter-round bilges whose radius progressively increases rearwardly throughout, and a middle body having rounded bilges throughout merging with the foreand afterbody bilges, all bilges being convex throughout.

14. A displacement type hull having vertical sides throughout and a flat bottom, said hull including a middle body whose sides are parallel and duplicate foreand afterbodies, the sides of the forebody approaching each other forwardly throughout to a pointed bow and the sides of the afterbody approaching each other rearwardly throughout to a pointed stern, the foreand afterbodies having rounded bilges whose radius increases progressively forwardly throughout in the case of the forebody and rearwardly throughout in the case of the afterbody, each of said bilges being in the form of a quarter section of a truncated cone bent longitudinally with the center element of the conical surface intersected by lines bisecting the right angle between the contiguous side and bottom portions, and the middle body having uniform rounded bilges merging with the foreand afterbody bilges, all bilges being convex throughout.

15. A displacement type hull having vertical sides throughout and a flat bottom, said hull ineluding a middle body and foreand afterbodies,

the forebody sides approaching each other forwardly throughout to a pointed bow and the ar'terbody sides approaching each other rearwardly throughout to a pointed stem, the foreand afterbodies having arcuately rounded bilges throughout, the side tangency line of each forebody bilge inclining upwardly and forwardly throughout and the bottom tangency line of each forebody bilge inclined inwardly toward the longitudinal center and forwardly throughout, the side tangency line of each afterbody bilge inclining upwardly and rearwardly throughout and the bottom tangency line of each afterbody bilge inclining inwardly toward the longitudinal center and rearwardly throughout, the bottom tangency lines of the forebody terminating in an upwardly and forwardly curving line in the longitudinal center plane, the bottom tangency lines of the afterbody terminating in a rearwardly and upwardly curving line in the longitudinal center plane, and said middle body having arcuately rounded bilges throughout merging with the foreand afterbody bilges, all bilges being convex throughout.

WILLIAM STARLING BURGESS. 

